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METHOD OF MAKING] TAPERED DISK WHEEL Original. Filed Sept. 26. 1960 16Sheets-Sheet 16 United States Patent 01 fice 3,391,439 Patented July 9,1968 3,391,439 METHOD OF MAKING TAPERED DISK WHEEL Walter W. Bulgrin,Akron, Ohio, and Gordon C. J. Parent, Southgate, Mich., assignor to TheFirestone Tire & Rubber Company, Akron, Ohio, a corporation of OhioContinuation of application Ser. No. 58,580, Sept. 26, 1960. Thisapplication June 29, 1966, Ser. No. 565,035 3 Claims. (Cl. 29-159.01)

ABSTRACT OF THE DISCLOSURE This application is a continuation of ourapplication Ser. No. 58,580, filed Sept. 26, 1960, now abandoned.

The invention relates to an improved continuous operation for producingdisk wheels of conventional shape and cross section having optimumphysical characteristics, and more particularly to a continuouswheel-making operation comprising a minimum number of steps.

Conventional disk wheels for automotive vehicles are gene-rallybowl-shaped with a flat hub portion and a curved intermediate portionterminating in a cylindrical rim flange, and usually having an annularshoulder or nave therein. The cross sectional thickness tapers from thehub out to a relatively thin rim flange. The thin rim flange reducesweight at the periphery of the wheel while still providing adequateresiliency and impact strength. Hand holes are formed in the curvedintermediate portion to provide spoke portions and further reduce weightand increase resiliency, and to provide access for inflating dualwheels.

Various methods have been practiced for producing such disk wheels,including a series of die-forming operations, a combination of extrudingand die-forming operations, and a combination of hot or cold rolling aflat blank to taper it and thendie-forming. In all of such methods ofwhich we are aware, the metal is improperly stressed or inadequatelyworked to produce optimum physical characteristics in the final product.

The present invention contemplates making the disk wheel by coldspinning the curved bowl of tapering thickness from a flat blank withoutimproperly stressing the metal, to obtain optimum physicalcharacteristics requiring a minimum of die-forming to shape the diskinto final form.

Certain prior attempts have been made to produce disk wheels byspinning, but in such cases the wheel was unduly stressed radially bythe spinning operation itself or by forming operations before or afterthe spinning operation in order to produce the desired curved bowl shapeof tapering thickness.

It is an object of the present invention to provide an improved methodand apparatus for producing a disk wheel from a flat blank by spinningand die forming operations which do not unduly stress the metal.

Another object is to provide an improved method and apparatus forcontinuously producing disk wheels in a minimum number of operations.

A further object is to produce an improved wheel disk of curved bowlshape with tapering thickness having optimum physical characteristics.

A still further object is to produce an improved wheel disk and rimassembly.

Other objects include the provision of improved blanking means, improvedspinning means, improved die-forming and piercing means, improved diskand rim assembling means, and improved welding means, all cooperating tocarry out the improved method of producing an improved disk wheel andrim and disk assembly.

These and ancillary objects are accomplished by the improved methods,apparatus and articles comprising the present invention, preferredembodiments of which are shown by way of example in the accompanyingdrawings and described in detail herein. Various modifications andchanges in details of construction are comprehended within the scope ofthe invention defined in the appended claims.

In carrying out the invention, a flat circular disk is blanked,edge-machined, and then spun on a mandrel in such manner as to formcurved bowl shape of tapering thickness by progressively displacingelements of the metal axially on a curved mandrel while maintaining theouter diameter of the disk constant, then die-forming the bowl intofinished shape without unduly stressing the intermediate curved portionthereof, piercing the hand holes and hub bolt holes in the formed disk,press fitting the formed disk into a rim, and finally circumferentiallywelding the rim to the disk.

In the drawings:

FIG. 1 is a block diagram showing the sequence of the principaloperations in making disk wheels according to the present invention.

FIG. 2 is a perspective of the flat circular blank from which the bowlportion of the wheel is formed.

FIG. 3 is a perspective view representing the blank after machining itsouter edge.

FIG. 4 is a perspective view of the spun bowl.

FIG. 5 is a perspective view of the bowl die-formed into finished shape.

FIG. 6 is a perspective view of the formed bowl after piercing boltholes in the hub portion.

FIG. 7 is a perspective view of the formed bowl after piercing handholes in the intermediate portion.

FIG. 8 is a perspective view showing the finished bowl pressed into arim.

FIG. 9 is an enlarged fragmentary sectional view showing the bowl andrim welded together.

FIG. 10 is a schematic elevational view of the hydraulic stack lifterand roll feeder which automatically feeds plates one at a time to theblanking press.

FIG. 11 is a cross sectional view of the improved blanking operation.

FIG. 11a is a detached cross secional view of the upper female die ring.

FIG. 12 is a schematic plan view of the mechanism for taking the blanksfrom the press and stacking them.

FIG. 12a is a side elevation thereof.

FIG. 13 is a schematic plan view of the improved spinning apparatus.

FIG. 14 is a front elevation thereof.

FIG. 15 is an enlarged schematic view showing the edge-turning andchamfering operations.

FIG. 16 is an enlarged elevational view, partly in section, showing theimproved spinning operation.

FIG. 17 is a cross sectional view showing the improved forming andrestriking operation.

FIG. 18 is a reduced cross sectional view showing the improved bolt holepiercing operation.

FIG. 19 is a cross sectional view showing the improved hand holemultiple piercing operation.

FIG. 19a is a detached fragmentary sectional view showing the type ofhand holes pierced with the apparatus of FIG. 19.

FIG. 20 is a cross sectional view showing the improved hand hole singlepiercing operation.

'FIG. 20a is a detached fragmentary sectional view showing the type ofhand holes pierced with the apparatus of FIG. 20.

FIG. 21 is a cross sectional view illustrating the coining operation forthe hand holes of FIG. 19a.

FIG. 22 is a cross sectional view illustrating the coining operation forthe hand holes of FIG. 20a.

FIG. 23 is a fragmentary cross sectional view showing the operation ofdrilling and countersinking the bolt holes.

FIG. 24 is a cross sectional view showing the operation of boring andchamfering the hub hole.

FIG. 25 is a cross sectional view showing the operation of pressing thebowl into one type of rim.

FIG. 26 is a similar view showing the operation of pressing a differenttype of rim onto the bowl.

FIG. 27 is an elevational view of the welding apparatus for welding thebowl to the rim, showing the sup porting table in position to receivethe bowl and rim assembly after the pressing operation of FIG. 25 orFIG. 26.

FIG. 28 is a similar view showing the table assembly swung upwardly tobring the assembly into welding position for the welding torch.

FIGS. 29 and 30 are fragmentary sectional views showing a burn-throughtype of weld applied to different types of assemblies.

FIGS. 31 and 32 are similar views showing different types of weldsapplied to other types of assemblies.

In making a wheel disk having the conventional shape with taperingthickness shown in perspective in FIGS. 7 and in cross section in FIGS.19a and 20a, the wheels are spun from the flat circular edge-machineddisk B shown in FIG. 3 to the intermediate bowl shape C of FIG. 4 (shownin cross section in FIG. 16), and then dieformed to the finished shape Dof FIG. 5 (shown in cross section in FIG. 17), followed by holepiercing, coining and machining operations which will be described indetail.

Before machining, the disks A (FIG. 2) are blanked from flat steelplates or shets which are fed, one at a time, to a blanking press inwhich are mounted the blanking dies shown in FIGS. 11 and 12.Preferably, a hydraulic stack lifter, magnetic roll sheet gripper androll feeder, shown in FIG. 10, automatically feed the plates from astack supported on a hydraulic lift.

Referring to FIG. 10, the plate feeding apparatus comprises a base frameindicated generally at 11 and having upright stanchions 12 andhorizontal cross support members 13. A supporting table 14 is verticallyslidable between the stanchions 12 and is raised by hydraulic liftcylinders 15 actuating piston rods 16 to raise the table and a stack ofplates S supported thereon.

A horizontal series of rolls, preferably in groups of three, issupported in the cross members 13 and arranged to be contacted by thetop plate in the stack when the stack is lifted. In each group of threerolls the middle roll 17 is a drive roll and the two end rolls 18 aremagnetic rolls. The drive rolls are interconnected by a drive chainwhich is driven from a pulley 19 driven by a motor 20, and the magneticrolls 18 are dapted to be energized by electric current in a well-knownmanner. A pressure switch roll 21, which extends slightly below thelevel of the rolls 17 and 18 is adapted, when contacted by the top platein the stack S, to energize the magnetic rolls 18 and start the motor todrive the intermediate rolls 17, at the same time shutting off presurefluid to the cylinders 15 to allow the table 14 to descend. The magneticforce of the rolls 18 is regulated so that only the top sheet S will beheld by the magnetic rolls as the stack S descends. A limit switch 22 ontable 14 is actuated when the bottom 4 plate of the stack is removed,and the switch 22 is in circuit with the control for the hydraulic lifts15, so that the table can not be raised until a new stack of plates S isloaded thereon.

The drive rolls 17 move the top sheet S to the left as viewed in FIG. 10and it is engaged by the pinch rolls 23 and conveyed onto the conveyorrolls 24 which may also be driven by suitable chain drives from themotor 20. At the outer end of the table is another pair of pinch rollsindicated at 25 which feeds the sheet into the blanking press. Thisautomatic plate feeder may be controlled by the same man who operatesthe blanking press.

The blanking operation Referring to FIGS. 11 and 11a, the blanking diesare mounted in a conventional press and comprise an upper punch holder26 connected to the press ram 27, and a lower die shoe 28 supported onthe bed or table of the press. The die shoe has a central bore 29through which the central slug punched out of the blank is discharged,and an annular hub hole die 30 and backing plate 31 are supported on topof the die shoe around the central hole 29. An annular male die ring 32is carried on the upper surface of the die shoe 28 and is adapted totelescope within a female die ring 33 carried on the bottom of the upperdie holder 26. Retainer clamp blocks 34 are secured by screws 35 to thedie shoe 28 and clamps the male die ring 32 and the hub hole die 30 tothe die shoe. The female die ring 33 is similarly clamped to the dieholder 26, and preferably a spacer ring 36 is secured to the die holderaround the base of the ring 33 to allow for replacing the ring 33 withlarger die rings.

The center punch 37 is secured to the die holder 26 by retainer clampring 38 and a stripper plate 39 surrounds the center punch 37 within thefemale die ring 33. The stripper plate is carried by guide rods 40 whichare attached at their upper ends to a bridge plate 41 movable in arecess 42 in the die holder and urged upwardly by compression springs43. A removable knockout bar 44 on the press ram is adapted to engagethe bridge plate 41.

In the blanking operation, a plate S is fed across the male die ring 32with the ram in raised position. As the press is operated to lower therain the male die ring telescopes within the female ring 33 to shear acircular blank and simultaneously punch a circular hub hole at thecenter of the blank. Referring to FIG lla, the female die ring 33 has aseries of inclined portions 33a, 33b in its lower edge to provide ashearing action as it telescopes over the male die. Similarly, thebottom portion of the center punch 37 is provided with inclined portionsas shown in FIG. 11 to obtain a shearing action as the punch passesthrough the center of the blank.

As the circular blank A is sheared from the plate S, the stripper plate39 retracts to allow the blank A to pass into the female die 33 where itis held by friction as the ram and die holder 26 are raised. Theknockout bar 44 is then operated to push the stripper plate 33 down andstrip the blank A from the female die. As the blank is sheared, thescrap metal at one side of the male die is held against a pressure block45 by lifting arms 46 supported on guide rods 47 extending through thedie shoe. The scrap metal on the other side of the die ring is deflectedaway from the die shoe by a recess Referring to FIGS. 12 and 12a, theblanking press is indicated generaly at P, and has the knockout bar 44extending transversely through the ram 27 for stripping the blank A fromthe female die as the ram ascends. A sliding carriage 12-1 is mounted ona frame 12-2 on the discharge side of the press for movement to and fromthe position under the ram shown in full lines.

A fluid cylinder 12-3 is mounted atop the frame 122, and has a pistonrod 12-4 attached to a flange on the carriage. The inner end of thecarriage has inclined portion 12S which is adapted to move under the ramand receive the blank therefrom, and a transverse stop bar 12-6 at thebase of the inclined portion normally retains the blank thereon. Theends of the stop bar are movable upwardly in slotted brackets 12-7, andare engaged by cam blocks 12-8 on the frame as the carriage moves awayfrom the press, to release the blank and allow it to drop from theinclined portion 12-5 onto a slatted conveyor 12-9 driven by a motor1210 on the lower part of frame 12-2.

Assuming the carriage 12-1 is in the full line position of FIGS. 12 and12a, and a plate S is in the phantom position against a retractible stop12-11, as the ram 27 descends a micro switch M is actuated by a cam onthe ram and energizes a solenoid valve (not shown) to operate the pistonrod 12-4 and move the carriage to the left out of the way of the ram. Oncompletion of the downstroke the circular blank A is punched out andheld in the upper female die as the ram is raised, as

previously described.

As the carriage moves to the left the blank A thereon from the previouspunching operation is released when the transverse stop bar is raised bycontact with the cam blocks 128, and drops onto the slatted conveyor12-9.

As the ram starts to rise it actuates micro switch M and energizes asolenoid valve (not shown) to reverse the piston rod 21-4r and returnthe carriage to its position under the ram. Further rise of the ramcauses the knockout bar to drop the blank on the inclined portion 12-5of the carriage which actuates a micro switch M on the carriage incircuit with micro switch M causing the carriage to move to the leftwith the blank thereon. Should there be no blank on the carriage,actuation of micro switch M by the descending ram will neverthelesscause the carriage to move to the left out of the way of the press.

A micro switch M connected with the press operating circuit is mountedon the frame 12-2, and is adapted to be closed by the carriage when itreaches its extreme left position. Accordingly, the ram cannot beoperated to descend unless the carriage is at its extreme left position.

The conveyor 12-9 discharges the blanks successively onto a rollerdischarge chute 12-12, which in turn guides the blanks onto a table12-13 where they strike against a vertical stop 12-14 and form a stackof blanks. Side gates 12-15 form guide walls on opposite sides of thestack, and the gates are vertically slidable in vertical guide bars12-16. Fluid motors 12-17 are adapted to operate lift chains 12-18attached to said gates 12-15 and allow a stack of blanks to be conveyedlaterally in either direction by a drag chain 12-19 on conveyor rollerswhich deliver the stack to the spinning operation.

The fluid motors 12-17 may be operated to raise the gates 12-15 by amicro switch M which is actuated by the stack of blanks when it reachesa predetermined height. The gates 12-15 are preferably adjustablerelative to each other for various sizes of blanks by means of adjustingscrews 12-20 on the frame 12-21.

The spinning operation Referring to FIGS. 13 and 14, stacks of theblanks A are conveyed or taken to a feeder conveyor 50 which feeds thestacks successively onto the table 51 of a stack lifter 52. The table 51is raised and loweredby a vertical screw 53 which is driven by a motor54 through a gear box 55.

The height to which the stack is raised is determined by a limit switch(not shown) which contacts the top blank A on the stack, and a transferarm 56 has a finger at its outer end which engages in the hub hole ofthe top blank only. A hydraulic cylinder 57 actuates the transfer arm 56to slide a top blank A from the stack onto a swinging lift rack 58 whenthe rack is in the horizontal position shown in FIG. 13.

The transfer arm 56 is connected by a floating pivot 59 to one end of anarm 66, the other end of which is pivoted at 61 on the base of themachine. The outer end of transfer arm 56 has a slot 62 engaging astationary pin 63 on the machine. This arrangement provides fortransferring the top blank A from the stack in a straight linelongitudinally of the machine onto the rack 58.

The rack 58 is pivoted at its inner end on a base 64 for swinging from ahorizontal to a vertical position and may be actuated by any suitablemeans (not shown). The swinging movement of the rack 58 is suitablycoordinated with that of the transfer arm 56 so that when a blank isplaced on the rack the arm returns to pick up another blank from thestack, and the rack swings to the vertical position of FIG. 14.

When the rack 58 is in vertical position, the blank A thereon is alignedwith a longitudinal track 65 adapted to guide a series of blankslongitudinally of the machine. A traveling arm 66 extends alongside ofthe track and has a plurality of depending arms 67 having fingers attheir lower ends adapted to engage the hub holes of blanks on the track65. The fiinger on the rearmost arm 67 is adapted to engage in the blankA supported on the rack 58' in vertical position.

The traveling arm 66 is reciprocated by a hydraulic cylinder 68controlled by suitable controls such as limit switches, not shown. Asthe arm 6-6 is reciprocated, the blanks A are advanced longitudinallyalong the track 65 step-by-step to the various stations or positions A-A shown in FIG. 14, and when a blank A is advanced from the rack 58onto the track 65, the rack swings back to horizontal position toreceive the next successive blank from the transfer arm 56.

When a blank reaches the station A the outer edge surface thereof ismachined and one corner is chamfered. At this station is a tailstock 69movable on a transverse slide 70 and having a nose which is insertedthrough the hub hole of the blank, and displacing the blank so that thenose fits in the spring-loaded spindle 71 of the headstock 72. With theblank in this position, the spindle is then rotated by a drive beltindicated at 73, and the blank is engaged by a turning tool 74 on oneside and by a diametrically opposite chamfering tool 75 (see FIG. 15).The turned and chamfered disk is designated B in FIGS. 3 and 15.

The disk B is then advanced along the track 65 to the positions A; and Asuccessively. At the position A a suitable lubricant is applied to onesurface of the disk to prepare it for the spinning operation. Thislubricant may be applied by a device indicated generaly at 76 which hasa spindle 77 for rotating the disk while pressing a bar of tallow or thelike against the surface of the disk.

When each disk B reaches station A it enters a rack 78 supported on aturntable 79, the aligned position of the rack being indicated inphantom in FIG. 14. The turntable is then rotated 90 to the full lineposition shown in FIGS. 13 and 14 so that the disk B is positionedtransversely of the machine. in this position, the disk B is adapted tobe picked up by an overhead traveling arm indicated at 80 in FIG. 14 andcarried forward to the spinning mandrel 81.

The lifting arm 80 is mounted on a carriage S2 and is raised or loweredby a hydraulic cylinder 83 on said carriage. A second lifting arm 84 issimilarly mounted on said carriage to the rear of arm 80 and is adaptedto be raised and lowered by hydraulic cylinder 85 on said carriage. Thecarriage 82 is movable along a longitudinal beam 86 by means of rollers87 rolling on the top and bottom of the beam. The carriage is attachedto a drive chain 88 which is driven by a motor 89 and chain 90 forreciprocating the carriage back and forth on the beam 86.

Each of the arms 80 and 84 have at their lower ends toggle clampsindicated generally at 91 and 92, respectively, having clamping jawswhich preferably are open ated by compressed air cylinders. The frontclamp 91 is adapted to pick up and advance the disks B while the rearclamp 92 is adapted to pick up and return the spun bowls C from thespinning operation. When the front arm 80 has positioned a disk B facingthe mandrel 81, the tailstock 93 is slid forwardly on the base 94 toengage the nose 95 of the floating spindle 96 of the tailstock in thehub hole of the disk, and as the nose enters the mandrel (FIG. 16) theclamp 91 releases the disk and arm 80 is raised. The spindle 96 has amagnetic stop plate 97 at the base of the nose 95 so that when thetailstock is retracted at the end of the spinning operation, the spunbowl C will be stripped from the mandrel 81, When the tailstock 93 isretracted to the position of FIGS. 13 and 14, the bowl C is strippedfrom the nose 95 by diametrically opposite stripper pins 98 mounted in aframe 99 on the tailstock base 94.

Just before the bowl is stripped from the nose 95, the rear lifting arm84 is lowered and the clamp 92 clamps the bowl, and then when the bowlhas been stripped from the nose the arm raises the bowl to the upperposition indicated in FIG. 14 and the carriage is retracted to positionthe bowl over an inclined discharge chute 100, as indicated in fulllines in FIGS. 13 and 14. The clamp 92 then releases the bowl C into thechute and the front arm 80 descends with its clamping jaws open to pickup the next disk B, whereupon the carriage again moves forward and theoperation is repeated.

The spinning mandrel 81 is rotatably mounted on a headstock 101 and isdriven by a motor 102 through a belt drive 103. The spinning tool ortool ring 104 is journaled in a bearing housing 105 (FIG. 16) in a yoke106, and the yoke is carried on a cross slide 107 (FIG. 13) movable atright angles to the main slide 108 which is angularly movable on thebase 94 at an angle to the axis of the headstock 101. Thus the tool ring104 can be moved in two directions to follow the contour of the spinningmandrel 81, and the movement of the tool ring is controlled by atemplate 109 of proper contour, supported on the main slide and engagedby a tracer finger 110 on the cross slide. The main slide may beoperated by a suitable hydraulic ram 111, and the cross slide may beoperated by a suitable hydraulic ram 112.

By using suit-able and well-known controls such as limit switchesactuating solenoid valves controlling the operation of fluid cylindermeans for the various mechanisms, the entire operation from the stacklifter for the blanks A to dropping the spun bowls C into the dischargechute 100 is carried out automatically.

During the spinning operation, as the tool ring 104 is moved to followthe contour of the spinning mandrel 81, each circumferential element ofthe disk is displaced axially, but not radially, of the mandrel as thetool moves along the mandrel so that the outer diameter of the disk ismaintained constant at all times and the outer diameter of the finishedbowl is accordingly the same as that of the original disk. The contourof the spinning mandrel is such that as the circumferential elements ofthe disk are successively displaced axially the thickness of the disk isgradually tapered to compensate for the axial displacement and maintainthe constant outer diameter. The intermediate portion of the disk may bearcuate or a parabolic curve, and the thickness tapers in proportion tothe sine of the angle formed by the tangent at any point on said curvewith respect to the axis of the finished bowl; or, stated another way,the thickness tapers in accordance with the progressive change in thesine of the angle formed betwen the tangent to said curved portion andits axis. F or example, the thickness at the hub portion may beapproximately 2.5 times that of the thickness at the outer edge. Thus,the hub portion may be 0.375" thick, and the outer edge 0.156" thick.

Accordingly, the spinning operation performs a cold working of the metalwithout improperly stressing it, so that optimum physicalcharacteristics are obtained resulting in maximum strength andresiliency in the finished product. Because of the optimum physicalcharacteristics produced by the improved spinning operation, it is notnecessary to hot or cold work the disk prior to the spinning operation;nor is it necessary to subsequently treat the metal to relieve stressestherein.

Moreover, due to the curved path followed by the tool ring, the wear onthe spinning nose is distributed over its curved surface. Obviously, byproviding a symmetrical nose medially of the tool ring, additional toollife can be obtained by reversing the ring.

The die-forming operation The spun bowls C are taken from the dischargechute to a press of conventional construction in which are mounted theforming dies shown in FIG. 17. Attached to the ram of the press in theusual manner is the punch holder 114, and the die shoe is supported onthe bed or table of the press. Guide pins 116 are press-fitted intobores 117 in the die shoe, and are slidably received in bushings 118secured in bores 119 in the punch holder by retainer rings 120.

A punch backing plate 121 is secured to the under surface of the punchholder by screws 122, and is provided with a centering boss 123 receivedin a bore 124 in the punch holder. A forming punch ring 125 is heldagainst the backing plate 121 by screws 126 and a hub face restrikepunch 127 is slidably mounted in the punch ring 125. Annular shoulders128 and 129 on the punch ring and hub face restrike punch, respectively,limit the relative motion therebetween. Springs 130 located in the punchholder 114 and extending through the backing plate 121 yieldingly urgethe hub face restrike punch 127 downwardly.

The hub face restrike punch has an axial bore 131 which slides over anaxial centering plug 132 adapted to fit the hub holes in the bowls C andsecured in the die shoe 115 by a screw stud 133. Surrounding the punchring 125 is an annular flange stock guide 134 supported on the die shoeby brackets 135 and having circumferentially arranged spring centeringpins 136 to center a spun bowl C when it is placed in the guide 134before the ram and punch holder descend.

The female forming die is supported on a backing plate 137 seated in thedie shoe, and comprises a hardened central die pad 138 through which thecentering plug 132 extends. Surrounding the die pad is a cup-shaped dieretaining ring 139 which encloses and supports a contour die ring 140and a die ring 141 for forming the rim flange on the bowl. The outerannular surface of the retaining ring 139 is slightly tapered and iswedgeably held in position by a wedge ring 142 secured to the die shoeby screws 143. A clamping ring 144 holds the die ring 141 in placeagainst the upper surface of the contour ring 140.

In the operation of the forming dies, as the punch descends and entersthe bowl C positioned within the guide ring 134, the springs 130 causethe hub face restrike punch 127 to yieldingly engage the hub portion ofthe bowl before the punch ring 125 engages the curved rim of the bowl.When the hub portion bottoms, the punch ring 125 then draws the curvedportion of the bowl against the c011- tour die 140, and in order toprevent wrinkling or buckling of the rim portion of the bowl during thisoperation an annular beveled surface 145 is provided to substantiallyconform to the angle of the outer rim of the bowl C and allow the metalto be drawn gradually and smoothly into the flange rim R of the formedbowl D (FIG. 5

As seen in FIG. 17, the contour ring 140 cooperates with the punch ring125 to form the annular shoulder T in the formed bowl betmeen the flathub portion and the intermediate curved portion. The gradually taperingthickness from the hub portion to the outer rim of the bowl issubstantially maintained in the forming dies, although a slight thinningof the rim flange R may be accomplished.

The shock of the hub face restrike punch bottoming on the hub portion ofthe bowl is preferably cushioned

